High stocking densities in salmon aquaculture cause chronic stress, aggression, injury, and disease susceptibility, undermining both welfare and production outcomes.
Salmon are active, wide-ranging fish that in natural environments would never experience the densities common in net-pen aquaculture. Crowding causes chronic activation of the stress response, suppressing immune function and increasing susceptibility to disease and parasite infestation. Fin damage from aggression and abrasion against cage walls is nearly universal in high-density systems. Reducing stocking density is one of the most impactful and immediately actionable welfare improvements available to salmon farmers.